1. Field of the Invention
The invention relates to aqueous dispersions of organosilicon compounds, to processes for production thereof and to the use thereof, especially for hydrophobizing impregnation and bulk hydrophobization of mineral and organic building materials.
2. Description of the Related Art
Silanes and siloxanes have long been used for architectural protection, for example solutions of silanes in organic solvents as described, for example, in DE-A 1069057. For reasons of cost, but not least also because of the hazards to health when handling organic solvent and the associated environmental pollution, working with organic solvents is disadvantageous.
Aqueous formulations based on alkylalkoxysilanes and -siloxanes are known. EP-A 234 024 describes silane emulsions comprising nonionic emulsifiers having an HLB value of 4 to 15. EP-B 392 253 describes aqueous formulations comprising mixtures of alkoxysilane and alkoxysiloxanes. The addition of hydrophobic fillers, such as hydrophobic silica, can improve the bead-off effect of these formulations. However, no statement is made as to the stability of the emulsions on addition of hydrophobic silica. EP-B 582 611 too uses hydrophobic silica, without making any statements as to storage stability. If self-dispersing compositions are formulated with siloxanes having a high proportion of basic nitrogen, even a hydrophobic silica is stably dispersible (EP-B 609 524). However, such formulations tend to yellow and become discolored on use because of the amine content.